The long-term objectives of our work are to establish an MR imaging technique to detect early changes of psoriaticarthritis (PsA) in the hand, and use that technique to improve our understanding of the disease mechanism and the effect of early treatment on the outcome of the disease. The recent work showed detection of lesions and cortical erosions with fat suppressed T2 weighted MRI have a significant role in the early stage of the disease, The purpose of this work is to advance the MR imaging technology to allow the detection of small lesions and early bone erosions in Spa in the hand. The specific aims of this work are: 1) to develop specifically designed phased arramy RF receiver coils for the hand and fingers to provide high signal sensitivity for high-resolution imaging of these specific anatomies; 2) to develop MR pulse sequences that improve fat suppression while acquiring both fat suppressed and non-fat suppressed images in a single scan time; 3) to evaluate the effect of chemical shift artifact elimination on the accurate measurements of anatomic structures and lesions in hand and fingers; 4) to conduct pilot evaluation of the usefulness of the new RF coil and pulse sequence technology in the detection of lesions in Spa patients. To accomplish our goal we will use our previous experience on phased array RF receiver coils to the design of special coils for the hand and for the fingers. Those coils will be tested on phantoms and normal subjects, and suitable ones will be used for further studies. The new pulse sequence development to acquire separate water and fat data in a single imaging time will be based on our preliminary experience in interleaved water and fat 3D gradient recall echo and 2D spin echo sequence development using spatial spectral excitation pulses. This will be further implemented on 2D spin echo, and 2D and 3Dfast spin echo sequences. We will develop post-processing algorithms to reconstruct water-only, fat-only and water plus-fat images from the acquired data. The new sequences will be tested on phantoms and normal subjects and their performance will be compared to that of the existing sequences. Fifteen patients with PsA as determined by plain film X-ray of the hand will be imaged using our new MRI technology to test its usefulness to detect PsA lesions. After completion of this study we will have the technology to detect early changes in PsA. This technology will allow us to start the clinical evaluation of the disease mechanism and the long-term effect of early treatment.